The present invention relates, in general, to methods for treating food products and, more particularly, to methods for reducing pathogenic microorganism populations on food commodities during food processing.
Microbial outgrowth is a primary cause of food spoilage. The presence of pathogenic microorganisms on food products can potentially led to food-borne outbreaks of disease and can cause significant economic loss to food processors. The need to delay the onset of spoilage has lead the food processing industry to seek effective means for disinfecting food products in order to ensure food safety. Currently, food manufacturers use several different technologies to eliminate, retard, or prevent microbial outgrowth. For example, techniques such as heating, irradiation, and application of chemical agents are currently in use. However, the effectiveness of a particular technology can depend on the particular food product and type of microorganism present on the food product. Additionally, certain chemical agents can have a deleterious effect on human health. For example, chlorine has been widely used as a sanitizer for many years, however, chlorine can produce toxic by-products, such as chloramines and trihalomethanes.
Another widely used chemical agent is ozone (O3). Ozone is a very strong oxidizing agent, having an oxidation potential more than 1.5 times that of chlorine and approximately 1.3 times that of hydrogen peroxide. Ozone is normally produced by irradiating an oxygen-containing gas with ultraviolet light or corona discharge. Ozone has been widely used as a disinfectant in the food industry for many years. Processes have been developed that use gaseous ozone to sterilize and disinfect food products. Although applying gaseous ozone to food products can be an effective means of controlling microbial outgrowth, an effective method of applying the ozone to the food product must be available.
To address the public health concern associated with food contamination, development of more effective processes to ensure safe and wholesome food production has become a main strategy for the food industry. Processes for the separate application of ozone and steam in a vacuum and pressure regulated environment have been developed to improve the effectiveness of ozone at killing the bacteria present on food. In addition, continuous processes have been developed that include spraying ozone gas and a mixture of ozone and water directly onto animal carcasses immediately after slaughter.
Despite recent development of ozone application technology, food contamination by pathogenic microorganisms continues to be a significant health problem. According to recent statistics from Centers for Disease Control (CDC), there are approximately 76 million cases of food borne illness in the United States annually. The most common food-associated pathogens are: Norwalk-like viruses, Campylobacter jejuni, and Salmonella. Escherichia coli 0157:H7 and Listeria monocytogenes can also cause severe illness. As the world population increases, the demand for processed food will also increase and food borne illness is more likely to become an even greater problem. To address this public health concern, development of more effective processes to ensure safe and wholesome food production continues to be an important objective of the food industry.
One primary objective of this invention is to treat a food commodity, such as meat and, preferably, chicken breasts, with a fluid comprising ozone, which can be a gas, a liquid, or liquid and gas mixture, in a sealed container to obtain a lower bacterial count without affecting its organoleptic properties (overall quality of taste, odor, and color). The amount of ozone injected is preferably as small as possible, while at the same time, showing a significant log reduction on bacteria count. Some water is preferably added to obtain better contact of ozone with the food commodity by forming a thin film of ozonated water on the surface of the food commodity. Spices and/or other ingredients may be added with the water.
In one preferred method, the invention generally includes, placing a food commodity, such as meat, poultry, fish, seafood, fruits and vegetables in a sealed container, such as a treatment chamber, which can be tumbler, or an apparatus configured to receive a tumbler. A vacuum is generated in the treatment chamber and either before or during vacuum generation, a treatment fluid comprising ozone is produced to obtain a steady stream of a treatment fluid flowing through a conduit, which is vented through an exhaust system.
Once a vacuum of at least 2 inches Hg, preferably a vacuum of around 25 inches of Hg is reached, the treatment fluid is injected into the treatment chamber. The treatment fluid is injected until the pressure inside the chamber rises to about atmospheric pressure. In certain preferred embodiments of the method, an excess of ozone is introduced in the treatment chamber at a pressure slightly above atmospheric pressure, or alternatively, a residual vacuum may be beneficial for certain treatment processes.
In one embodiment of the invention, the treatment fluid contacts the food commodity through action of a tumbler. The tumbler can function as the treatment chamber, or the tumbler can be positioned within a treatment chamber. Preferably, a small amount of water is injected to create a thin water film rich in ozone. This treatment is carried out for a time sufficient to obtain good disinfection, preferably about 50% reduction in bacterial count, without affecting food quality (color, odor, taste).
The present invention contemplates a number of different motion patterns of the tumbler. During the contact period, the tumbler is preferably rotated about a rotation axis. Alternatively, the tumbler can be agitated by alternatively rotating the tumbler about a rotational axis in both a clockwise direction and a counterclockwise direction for a predetermined period of time. In another embodiment of the invention, the tumbler is axially oscillated along a shaft. In yet another embodiment, the tumbler is vibrated in a vertical or horizontal reciprocating motion or both.
After the required time, the treatment fluid is purged from the treatment chamber so that it can be opened safely. In one embodiment, the treatment chamber and associated gas lines are purged by flushing with an inert gas, such as carbon dioxide and the like.